The present invention relates to porous filter blocks. More particularly, the invention relates to filter blocks utilized for filtration of melt synthetic plastic materials in a process of manufacturing fibers of plastics. The present invention further relates to a method of producing porous filter blocks, particularly those utilized for filtering melt synthetic plastic materials.
Known filters include a plurality of superimposed filter discs made from wire filaments of identical or various mesh sizes disposed in a desired row in a ring and bounded by this ring.
For example the allowed German application AS No. 23 18 190.0-27 discloses a filter block wherein filter discs or filter layers are enclosed by a profiled sheet ring so that all the sides of the filter discs will be subjected to tensile loads. The filter layers in the known arrangements may have a round or oval shape or any other desirable geometric form.
Known filter blocks produced by cold-pressing usually include a plurality of superimposed filter layers made out of wire. These layers have the same mesh size in the upper side, lower side and intermediate portion of the filterblock. Such known filterblocks, however can not be effectively used in a process of producing of fibers of plastics where filters with fine mesh of approximately 25 .mu.m are required for filtering melt synthetic plastic material.